Authorities are investigating possible cases involving four relatives of Santos, including a 13-year-old and a nine-year-old.

In the city centre and rural areas of Casimiro de Abreu, about 150 kilometres from Rio de Janeiro, a large tent has been set up to vaccinate people. Authorities say around 30,000 of the city’s 42,000 people have been vaccinated in recent days.

“I’m really scared,” said Tais da Silva Almeida, a mother of two who arrived Friday to get vaccinated. “If adults can’t deal with the illness, imagine the children.”

Transmitted by mosquito

Yellow fever is transmitted by mosquito and causes fever, body aches, vomiting and sometimes jaundice. Rio de Janeiro’s state Health Department has announced plans to vaccinate its entire population as a preventative measure. It says it will need 12 million doses to reach a 90 per cent vaccination rate by year’s end.

Fruit vendor Walace Santos’s brother, Watila Santos, died from yellow fever in Casimiro de Abreu, Brazil, on March 11. Walace Santos is glad that his brother’s death alerted authorities and will help save lives. (Leo Correa/Associated Press)

The vaccinations come as cases continue to be confirmed in several areas nationwide. Brazil’s Health Ministry says that at least 424 people have been infected with yellow fever in the largest outbreak the country has seen in years.

Of those, 137 have died, and more than 900 other cases are under investigation. The vast majority of confirmed cases and deaths have been in the southeastern state of Minas Gerais, which borders the state of Rio de Janeiro.

Experts monitoring primates

In Casimiro de Abreu, health workers visited houses in rural areas and inspected stagnant water, where mosquitoes lay eggs. The state also sent experts to nearby parks and reserves with monkey populations to monitor the situation with the primates, which are a primary reservoir of yellow fever.

Meanwhile, in a group of houses near a lush jungle area five kilometres from downtown, relatives of Santos wait for news about the four members of the family who may be infected.

Walace Santos, the younger brother of the man who died, said he took solace in knowing that the death raised alarm bells that could save others.

“Wherever he is now, he knows that because he died a lot of lives were saved,” said Santos.